Method for manufacturing high purity manganese and high purity manganese

ABSTRACT

The present invention relates to a method for manufacturing a high purity Mn, the method comprising: placing a flake-like electrolytic Mn raw material in a magnesia crucible to perform melting with the use of a vacuum induction melting furnace (VIM furnace) at a melting temperature of 1240 to 1400° C. under an inert atmosphere of 500 Torr or less; then adding calcium in a range between 0.5 and 2.0% of the weight of Mn to perform deoxidation and desulfurization; casting the resultant in an iron mold after the completion of the deoxidation and desulfurization to manufacture an ingot; then placing the Mn ingot into a magnesia crucible to perform melting with the use of a vacuum induction melting furnace (VIM furnace) at a melting temperature, which is adjusted to 1200 to 1450° C. and maintained for 10 to 60 minutes, under an inert atmosphere of 200 Torr or less; casting the resultant in an iron mold to manufacture an ingot; then placing the metal Mn ingot in an alumina crucible; reducing pressure to 0.01 Torr with a vacuum pump; and then heating to develop a sublimation and distillation reaction. Provided is a method for manufacturing a high purity metal Mn from a commercially available electrolytic Mn. In particular, an object is to obtain a high purity metal Mn in which the amount of impurities such as B, Mg, Al and Si is small.

TECHNICAL FIELD

The present invention relates to a high purity manganese (Mn)manufactured from a commercially available electrolytic manganese (Mn)and a manufacturing method thereof.

BACKGROUND ART

A method for manufacturing a commercially available metal Mn is anelectrolytic process in an ammonium sulfate electrolytic bath. In acommercially available electrolytic Mn obtained by this method,contained are about 100 to 3000 ppm of sulfur (S) and several hundredppm of carbon (C). Several hundred ppm of chlorine (CI) is alsocontained, and about several thousand ppm of oxygen (O) is furthercontained as it is an electrodeposit out of an aqueous solution.

As a method for removing S, O from the above electrolytic Mn, thesublimation purification method is well known among conventionaltechnologies. However, the sublimation purification method hasdisadvantages such as very expensive instrumentation and very pooryield. Further, even though the sublimation purification method canreduce S and O, a metal Mn obtained from the purification method will besubject to contamination due to the material of a heater, the materialof a condenser and the like in a sublimation purification apparatus. Forthis reason, disadvantageously, it is not suitable as a raw material forelectronic devices.

As a prior art, the following Patent Literature 1 describes a method forremoving S in metal Mn in which, at a melting temperature of an Mn oxidecompound such as MnO, Mn₃O₄ and MnO₂ and/or metal Mn, a material to beconverted into such an Mn oxide, for example Mn carbonate, is added, andmetal Mn to which an Mn compound has been added is melted under an inertatmosphere, and maintained in a molten state preferably for 30 to 60minutes to give a sulfur content of 0.002%.

However, Literature 1 does not contain any description about thecontents of oxygen (O), nitrogen (N), carbon (C) and chlorine (CI), anddoes not provide a solution for a problem that is caused when thesematerials are contained.

The following Patent Literature 2 describes a method for electrowinningmetal Mn, and a method for electrowinning metal Mn characterized in thatused is an electrolytic solution prepared by dissolving an excess amountof a high purity metal Mn in hydrochloric acid, filtering outundissolved materials to obtain a solution, neutralizing the solution bythe addition of an oxidizing agent, filtering out the resultingprecipitates, and then adding a buffering agent. It also describes amore preferable method for electrowinning metal Mn with the use of anelectrolytic solution prepared by further adding metal Mn to ahydrochloric acid solution of a metal Mn, filtering out undissolvedmaterials to obtain a solution, adding hydrogen peroxide and aqueousammonia to the solution, filtering out precipitates formed under weaklyacidic or neutral pH, and then adding a buffering agent.

However, although Literature 2 describes that S in a high purity Mn isreduced to 1 ppm, it does not have any description about the contents ofoxygen (O), nitrogen (N), carbon (C) and chlorine (Cl), and does notprovide a solution for a problem that is caused when these materials arecontained.

The following Patent Literature 3 describes a method for manufacturing ahigh purity Mn, and a method in which an ion-exchange purificationmethod using a chelating resin is applied to an aqueous Mn chloride, andthen the resulting purified aqueous Mn chloride is highly purified bythe electrowinning method. It is described that in a dry process, a highpurity Mn can be obtained from solid phase Mn by the vacuum sublimationpurification method (Mn vapor obtained by sublimation of solid phase Mnis selectively condensed and deposited as a purified material at acooling unit due to the difference in vapor pressures).

Further, Literature 3 describes that the total concentration of sulfur(S), oxygen (O), nitrogen (N) and carbon (C) is 10 ppm or less.

However, Literature 3 does not contain any description about the contentof chlorine (Cl) which has a deleterious effect on the manufacture ofsemiconductor components. Mn chloride is used as a raw material, andtherefore, disadvantageously, chlorine may be contained at a highconcentration.

The following Patent Literature 4 describes a method for manufacturing alow-oxygen Mn material in which an Mn material with oxygen reduced to100 ppm or less can be obtained by performing induction skull melting toan Mn raw material under an inert gas atmosphere, and the Mn rawmaterial is preferably subjected to an acid wash before induction skullmelting in view of further reducing oxygen. However, although Literature4 has a description about the reduction of oxygen (O), sulfur (S) andnitrogen (N) in a high purity Mn, it does not have any description aboutthe content of the other impurities, and does not provide a solution fora problem caused when these materials are contained.

The following Patent Literature 5 describes an Mn alloy material formagnetic materials, an Mn alloy sputtering target, and a magnetic thinfilm. Also described is that the content of oxygen (O) is 500 ppm orless, the content of sulfur (S) is 100 ppm or less, and further, thetotal content of impurities (elements other than Mn and alloycomponents) is preferably 1000 ppm or less. Further, the Literaturedescribes a method for removing oxygen (O) and sulfur (S) by adding, asdeoxidizing/desulfurizing agents, Ca, Mg, La and the like to acommercially available electrolytic Mn and then performing highfrequency melting. It also describes that vacuum distillation isperformed after preliminary melting for being highly purified.

With regard to the above Mn raw material, it is described that inExample 3, a deoxidizing/desulfurizing agent is added, and then highfrequency melting is performed to give an oxygen content of 50 ppm and asulfur content of 10 ppm (Table 3). In Example 7, vacuum distillation isperformed after preliminary melting to give an oxygen content of 30 ppmand a sulfur content of 10 ppm (Table 7). Moreover, in these Examples,about 10 to 20 ppm of Si and about 10 to 30 ppm of Pb are contained.

However, the purity of Mn manufactured according to the following PatentLiterature 5 is at a 3N level, and a high purity Mn, such as thatobtained from the present invention, could not be obtained. Further, inExample 3 of the following Patent Literature 5, high frequency meltingis performed after adding a deoxidizing/desulfurizing agent. Therefore,disadvantageously, a deoxidizing/desulfurizing agent may contaminate Mnto reduce the purity. In the case of Example 7, vacuum distillation isperformed after preliminary melting. Therefore, disadvantageously, amanufacturing cost is high because 99% or more of dissolved Mn issubject to volatilization.

The following Patent Literature 6 describes a method for manufacturing ahigh purity Mn material and a high purity Mn material for forming a thinfilm. In this case, it is described that preliminary melting of crude Mnis performed at 1250 to 1500° C., and then vacuum distillation isperformed at 1100 to 1500° C. to obtain a high purity Mn material. Thedegree of vacuum when performing vacuum distillation is preferably5×10⁻⁵ to 10 Torr.

The total impurity content in a high purity Mn obtained as describedabove is 100 ppm or less: Oxygen (O): 200 ppm or less, Nitrogen (N): 50ppm or less, Sulfur (S): 50 ppm or less and Carbon (C): 100 ppm or less.This is followed by examples in which the oxygen content is 30 ppm, andother elements are contained less than 10 ppm in Example 2 (Table 2).However, even in this case, the impurity level has not reached theintended level.

In addition, the following Patent Literature 7 describes a sputteringtarget comprising a high purity Mn alloy. Patent Literature 8 describesa method for recovering Mn using sulfuric acid. Patent Literature 9describes a method for manufacturing metal Mn in which Mn oxide issubjected to heat reduction. However, none of the above describesdesulfurization in particular.

In view of the above, the present inventors have proposed a method formanufacturing a high purity Mn, comprising leaching an Mn raw materialin acid, filtering out residues and using the filtrate for the cathodeside in electrolysis; the above method for manufacturing a high purityMn, further comprising degassing the above electrolytic Mn to reduce theCI content in the above electrolytic Mn to 100 ppm or less; and themethod for manufacturing a high purity Mn, further comprising degassingthe above electrolytic Mn material, and performing melting under aninert atmosphere to manufacture Mn where Cl≦10 ppm, C≦50 ppm, S<50 ppm,and O<30 ppm (see Patent Literature 10).

This method is effective for producing a high purity Mn. An object ofthe present invention is to provide a manufacturing method capable ofachieving a higher purity and reducing cost. Another object is toprovide a high purity Mn.

-   Patent Literature 1: Japanese Patent Application Laid-Open No.    S53-8309-   Patent Literature 2: Japanese Patent Application Laid-Open No.    2007-119854-   Patent Literature 3: Japanese Patent Application Laid-Open No.    2002-285373-   Patent Literature 4: Japanese Patent Application Laid-Open No.    2002-167630-   Patent Literature 5: Japanese Patent Application Laid-Open No.    H11-100631-   Patent Literature 6: Japanese Patent Application Laid-Open No.    H11-152528-   Patent Literature 7: Japanese Patent Application Laid-Open No.    2011-068992-   Patent Literature 8: Japanese Patent Application Laid-Open No.    2010-209384-   Patent Literature 9: Japanese Patent Application Laid-Open No.    2011-094207-   Patent Literature 10: Japanese Patent Application Laid-Open No.    2013-142184

SUMMARY OF INVENTION Technical Problem

An object of the present invention is to provide a high purity Mnmanufactured from a commercially available electrolytic Mn and amanufacturing method thereof. In particular, the present invention aimsto provide a high purity Mn that has a significantly lower impuritycontent and is manufactured at a lower cost as compared with theconventional technology.

Solution to Problem

The present invention solves the above problems, and provides thefollowing invention.

1) A method for manufacturing a high purity Mn, the method comprising:placing an Mn raw material in a magnesia crucible to perform meltingwith the use of a vacuum induction melting furnace (VIM furnace) at amelting temperature of 1240 to 1400° C. under an inert atmosphere of 500Torr or less; then adding calcium (Ca) in a range between 0.5 and 2.0%of the weight of Mn to perform deoxidation and desulfurization; castingthe resultant in an iron mold after the completion of the deoxidationand desulfurization to manufacture an ingot; then placing the Mn ingotin a magnesia crucible to perform melting with the use of a vacuuminduction melting furnace (VIM furnace) at a melting temperature, whichis adjusted to 1200 to 1450° C. and maintained for 10 to 60 minutes,under an inert atmosphere of 200 Torr or less; casting the resultant inan iron mold to manufacture an ingot; then placing the metal Mn ingot inan alumina crucible; reducing pressure to 0.01 to 1 Torr with a vacuumpump; and then heating to develop a sublimation and distillationreaction for obtaining a high purity Mn.2) The method for manufacturing a high purity Mn according to 1),comprising, when performing the sublimation and distillation, placingthe metal Mn ingot in a cylindrical alumina crucible and verticallyaligning a similarly-shaped alumina cylinder (a cooling cylinder) on topof the above cylindrical crucible to develop a sublimation anddistillation reaction so that Mn deposits inside the upper aluminacylinder.3) The method for manufacturing a high purity Mn according to 1) or 2),comprising attaching a carbon heater to the outside of the cylindricalalumina crucible into which the above metal Mn ingot is placed, andperforming heating.4) The method for manufacturing a high purity Mn according to any oneof 1) to 3), comprising performing sublimation and distillationpurification at 1100 to 1250° C. and a sublimation rate of 20 to 184g/h.5) The method for manufacturing a high purity Mn according to any oneof 1) to 4), comprising, when the deposited amount ofsublimated/distilled Mn reaches 70% of the weight of the metal Mn ingotcharged into the alumina crucible during the sublimation/distillationstep, stopping the sublimation/distillation step.6) A high purity Mn having a purity of 4N5 (99.995%) or more except forgas components, wherein the total amount of impurity elements B, Mg, Al,Si, S, Ca, Cr, Fe and Ni is 50 ppm or less. Note that the gas componentelements in the present invention mean hydrogen (H), oxygen (O),nitrogen (N), and carbon (C). The same hereinafter.7) A high purity Mn having a purity of 5N (99.999%) or more except forgas components, wherein the total amount of impurity elements B, Mg, Al,Si, S, Ca, Cr, Fe and Ni is 10 ppm or less.8) A high purity Mn having a purity of 4N5 (99.995%) or more except forgas components, wherein O and N as the gas components are less than 10ppm respectively, and the total amount of impurity elements B, Mg, Al,Si, S, Ca, Cr, Fe and Ni is 50 ppm or less.9) A high purity Mn having a purity of 5N (99.999%) or more except forgas components, wherein O and N as the gas components are less than 10ppm respectively, and the total amount of impurity elements B, Mg, Al,Si, S, Ca, Cr, Fe and Ni is 10 ppm or less.

Note that each instance of the unit “ppm” used herein means “wtppm”.Except for nitrogen (N) and oxygen (O) which are gas component elements,analytical values for the concentration of each element were analyzedwith the GDMS (Glow Discharge Mass Spectrometry) method. Moreover, gascomponent elements were analyzed using an oxygen/nitrogen analyzer fromLECO Corporation.

Advantageous Effects of Invention

The present invention provides the following effects.

(1) A high purity Mn, which has a purity of 4N5 (99.995%) or more exceptfor gas components, and in which the total amount of impurity elementsB, Mg, Al, Si, S, Ca, Cr, Fe and Ni is 50 ppm or less, can be obtained.Further a high purity Mn, which has a purity of 5N (99.999%) or moreexcept for gas components, and in which the total amount of impurityelements B, Mg, Al, Si, S, Ca, Cr, Fe and Ni is 10 ppm or less, can beobtained.(2) Further each of O and N as gas components can be reduced to lessthan 10 ppm.(3) Without the need for special equipment, a common furnace can be usedfor manufacturing a high purity Mn at a lower cost and higher yield ascompared with the conventional distillation method.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 This shows a schematic diagram of a sequence of process stepsfrom a step of subjecting the Mn raw material to primary VIM (vacuuminduction melting), a secondary VIM step, and a sublimation anddistillation purification step through to the manufacture of highlypurified Mn.

DESCRIPTION OF EMBODIMENTS

Below, embodiments of the invention will be described in detail.

Commercially available (a 2N level) flake-like electrolytic Mn can beused as a raw material in the method for manufacturing a high purity Mnaccording to the present invention. However, there is no particularlimitation for the raw material since the method is not affected by thepurity of the raw material.

When manufacturing a high purity Mn, first, an Mn raw material is placedin a magnesia crucible, and subjected to melting with the use of avacuum induction melting furnace (VIM furnace) at a melting temperatureof 1240 to 1400° C. under an inert atmosphere of 500 Torr or less(primary VIM step).

If the temperature is less than 1240° C., Mn does not melt, and the VIMtreatment cannot be performed. If the temperature is more than 1400° C.,suspended materials of oxides and/or sulfides are re-melted into Mn dueto the high temperature. Therefore, the concentrations of magnesium(Mg), calcium (Ca), oxygen (O) and sulfur (S) after the primary VIM stepwill be in an order of hundreds of ppm to thousands of ppm, and theintended purity in the present invention ultimately cannot be achieved.Results are shown in Table 2.

Then, Ca in a range of 0.5 to 2.0% of the weight of Mn was graduallyadded to this molten Mn to perform deoxidation and desulfurization.After the completion of the deoxidation and desulfurization, theresultant is cast in an iron mold to manufacture an ingot. After coolingthe ingot, slags adhered to the ingot are removed.

Next, this Mn ingot is placed in a magnesia crucible to perform meltingwith the use of a vacuum induction melting furnace (VIM furnace) at amelting temperature, which is adjusted to 1200 to 1450° C. andmaintained for 10 to 60 minutes, under an inert atmosphere of 200 Torror less (secondary VIM step). Then, the resultant is cast in an ironmold to manufacture an ingot. After cooling the ingot, slags adhered tothe ingot are removed.

Here, in the primary VIM step, since Ca as a deoxidizing/desulfurizingagent is added to molten Mn during melting, a small amount of Ca iscontained in an Mn ingot after the primary melting, and the meltingpoint of Mn decreases. Therefore, even in a case where a temperature ofthe secondary VIM is in a temperature range lower than that of theprimary VIM, melting can be performed.

Further, in the secondary VIM step, the deoxidizing/desulfurizing agent(Ca) added during the primary VIM step can be removed. When atemperature of the secondary VIM is more than 1450° C., volatilizationloss of Mn significantly increases, resulting in a decreased yield andincreased cost; therefore, it is not preferable.

Next, this metal Mn ingot is placed in an alumina crucible, the pressureis reduced to 0.01 to 1 Torr with a vacuum pump, and then heating isperformed. Next, a sublimation/distillation reaction is developed at asublimation/distillation temperature of 1100 to 1250° C. to manufacturea high purity Mn. Mn volatilized by the sublimation/distillationreaction is guided to a cooling cylinder where deposited Mn isrecovered.

Note that preferably, the sublimation/distillation step is stopped whenthe amount of Mn recovered in the sublimation/distillation reactionreaches 70% of the weight of the Mn material charged in the aluminacrucible. This stop operation can prevent impurity elements which remainin the crucible from sublimating to contaminate Mn deposited in thecooling cylinder to reduce the purity. The outlines of this step areshown in FIG. 1.

In the case of Mn obtained by this manufacturing method, a high purityMn having a purity of 4N5 (99.995%) or more except for gas components inwhich the sum (the total amount) of impurity elements, B, Mg, Al, Si, 5,Ca, Cr, Fe and Ni is 50 ppm or less can be obtained.

Further, by changing the conditions in the abovesublimation/distillation purification, a high purity Mn having a purityof 5N (99.999%) or more in which the sum (the total amount) of impurityelements, B, Mg, Al, Si, S, Ca, Cr, Fe and Ni is 10 ppm or less can beobtained. Specifically, purification can be performed at asublimation/distillation temperature of 1200 to 1250° C.

Then, when performing sublimation purification, each of O and N as gascomponents can be reduced to less than 10 ppm.

A high purity Mn can be obtained by placing a metal Mn ingot in acylindrical alumina crucible for performing the sublimation anddistillation; vertically aligning a similarly-shaped alumina cylinder ontop of the above cylindrical crucible; and developing a sublimation anddistillation reaction to deposit Mn inside the upper alumina cylinder.

The structure is simple as cylindrical alumina crucibles (cylinders) arepiled, and equipment with such a structure contributes to the reductionin a manufacturing cost.

It is necessary to heat the cylindrical alumina crucible in which theabove metal Mn ingot has been placed. A carbon heater can be attached tothe outside of the crucible for heating. This equipment structure isalso simple, and contributes to the reduction in a manufacturing cost.

When performing sublimation/distillation purification, it is preferredto perform heating of the Mn inside the cylindrical alumina crucible at1100 to 1250° C. and at a sublimation rate of 20 to 184 g/h. In thiscase, the duration of sublimation/distillation purification is about 8to 75 hours.

By adjusting the temperature and sublimation rate of thesublimation/distillation purification, the amount of impurities can becontrolled. The sublimation/distillation rate is preferably 20 to 184g/h, more preferably 103 to 184 g/h.

Further, the sublimation/distillation reaction step was stopped when theamount of Mn recovered by deposition reached 70% (recovery rate) of theweight of the Mn raw material charged in the alumina crucible.

In the sublimation/distillation step, as distillation progresses, theimpurity concentrations in the raw material Mn increase, and impurityelements are sublimated more significantly at the final stage of thestep. Therefore, contamination of impurities into the distilled Mn canbe prevented by stopping the step when Mn recovered by depositionreaches 70 wt % of the weight of the raw material Mn.

EXAMPLES

Descriptions below with reference to Examples and Comparative Examplesare provided for purposes of better understanding of the presentinvention. The present invention shall not be limited by Examples orComparative Examples.

Example 1

As a starting material, a commercially available flake-like electrolyticMn (purity 2N: 99%) was used. Impurities in the raw material Mn were B:15 ppm, Mg: 90 ppm, Al: 4.5 ppm, Si: 39 ppm, S: 280 ppm, Ca: 5.9 ppm,Cr: 2.9 ppm, Fe: 11 ppm, Ni: 10 ppm, O: 720 to 2500 ppm, and N: 10 to 20ppm.

(Primary VIM Step)

The above Mn raw material was placed in a magnesia crucible, and meltingwas performed using a vacuum induction melting furnace (VIM furnace) ata melting temperature of 1300° C. under an inert atmosphere of 200 Torror less. Then, Ca in 1 wt % of the weight of Mn was gradually added tothis molten Mn to perform deoxidation and desulfurization. After thecompletion of the deoxidation and desulfurization, the resultant wascast in an iron mold to manufacture an ingot. After cooling the ingot,slags adhered to the ingot were removed.

Impurities in the ingot after this primary melting were B: 12 ppm, Mg:130 ppm, Al: 1.2 ppm, Si: 20 ppm, S: 3.4 ppm, Ca: 520 ppm, Cr: 0.25 ppm,Fe: 2.2 ppm, Ni: 1.4 ppm, O: 10 ppm, and N: 10 ppm. Results are shown inTable 1.

As shown in Table 1, Ca is increased in the cast Mn due to the Careduction step. Mg is also increased because Mg is a constituent elementof the magnesia crucible and susceptive to reduction by Ca, and aportion thereof contaminates the cast Mn. Meanwhile, the results revealsthat S is significantly decreased, and other elements are also reduced.

(Secondly VIM Step)

Next, the Mn ingot obtained from the primary VIM was placed in amagnesia crucible, and a secondary VIM was performed using a vacuuminduction melting furnace (VIM furnace) at a melting temperature, whichwas adjusted to 1400° C. and maintained for 30 minutes, under an inertatmosphere of 100 Torr or less. Then, the resultant was cast in an ironmold to manufacture an ingot. After cooling the ingot, slags adhered tothe ingot were removed.

Impurities in the ingot after this secondary melting were B: 10 ppm, Mg:13 ppm, Al: 1.9 ppm, Si: 20 ppm, S: 0.58 ppm, Ca: 25 ppm, Cr: 0.28 ppm,Fe: 2.4 ppm, Ni: 1.2 ppm, O: 10 ppm, and N: 10 ppm. Results are alsoshown in Table 1.

As shown in Table 1, the results reveal that Ca and Mg, which increasedin the primary melting, are significantly reduced after the secondarymelting. S is also reduced. This can be explained if volatile impuritiesare removed in the secondary melting.

TABLE 1 Sublimation/distillation purification Raw material ComparativeMn Primary VIM Secondary VIM Example 1-1 Example 1-2 Example 1-3 Example1 B 15 12 10 0.61 0.46 1.1 0.2 Mg 90 130 13 17 0.17 <0.01 20 Al 4.5 1.21.9 0.25 1.4 0.85 0.15 Si 39 20 20 0.28 1.2 3.6 0.05 S 280 3.4 0.58 0.070.02 0.04 0.03 Ca 5.9 520 25 7.3 2.1 1.9 30 Cr 2.9 0.25 0.58 0.05 0.691.4 0.05 Fe 11 2.2 25 <0.1 0.21 0.77 <0.1 Ni 10 1.4 0.28 0.03 0.08 0.180.01 O 2200 10 2.4 10 10 10 10 N 20 10 1.2 10 10 10 10 Heatingtemperature (° C.) 1300 1400 1100 1200 1250 1050 Sublimation rate (g/h)23 103 184 3

TABLE 2 Raw material Mn Primary VIM Secondary VIM Mg 90 150 500 S 280 10150 Ca 5.9 600 1100 O 2200 15 500 N 20 20 20 Heating 1400 1450temperature (°C.)

(Sublimation/Distillation Reaction Step)

The metal Mn ingot obtained through the above primary VIM step and thesecondary VIM step was placed in a cylindrical alumina crucible, and asimilarly-shaped alumina cylinder was vertically aligned on top of thiscylindrical crucible to develop a sublimation and distillation reaction.

After pressure was reduced to 0.1 Torr with a vacuum pump, heating wasperformed to develop a sublimation and distillation reaction of Mn.Then, Mn was allowed to be deposited inside of the upper aluminacylinder, and a high purity Mn was recovered therefrom. Note that thecylindrical alumina crucible into which the Mn ingot was placed washeated with a carbon heater attached to the outside of the crucible.

When performing sublimation/distillation purification, Mn in thecylindrical alumina crucible was heated to 1050 to 1250° C., and thesublimation rate was 3 to 184 g/h. In this case, the duration ofsublimation purification was about 8 to 75 hours.

The impurity removing effect of sublimation/distillation purification issignificantly affected by the heating temperature and thesublimation/distilling rate. Therefore, it is performed in varyingtemperatures within a range of 1050 to 1250° C. andsublimation/distilling rates within a range of 3 to 184 g/h, asdescribed above. Specific examples (Examples and Comparative Examples)are shown below.

Further, the sublimation/distillation step was stopped when the amountof Mn recovered in the sublimation/distillation reaction reached 70%(recovery rate) of the weight of the Mn raw material charged in thealumina crucible to prevent the distilled Mn from being contaminated byimpurities. In order to determine when the sublimation/distillation stepis to be stopped, the relationship between the heating temperature andthe sublimation/distillation rate is preliminarily investigated, and theamount of Mn to be deposited in a sublimation/distillation rate at eachheating temperature is calculated to determine the time to stop thestep.

Impurities Associated with Heating Temperature and Sublimation Rate inSublimation Purification Comparative Example 1

In a case where sublimation/distillation is performed at a heatingtemperature: 1050° C. and a sublimation rate: 3 (g/h), impurities in themetal Mn after this sublimation purification were B: 0.2 ppm, Mg: 20ppm, Al: 0.15 ppm, Si: 0.05 ppm, S: 0.03 ppm, Ca: 30 ppm, Cr: 0.05 ppm,Fe<0.1 ppm, Ni: 0.01 ppm, O<10 ppm, and N<10 ppm. Results are shown inTable 1.

In this case, since the temperature was low and the sublimation rate wassmall, the effects of sublimation purification were not sufficient, andthe intended purity of 4N5 (99.995%) or more in the present inventionwas slightly unachievable. This is provided as the Reference Example orComparative Example.

Example 1-1

Sublimation/distillation purification was performed at a heatingtemperature of 1100° C. and a sublimation rate of 23 (g/h).

Impurities in the metal Mn after this sublimation purification were B:0.61 ppm, Mg: 17 ppm, Al: 0.25 ppm, Si: 0.28 ppm, S: 0.07 ppm, Ca: 7.3ppm, Cr: 0.05 ppm, Fe<0.1 ppm, Ni: 0.03 ppm, O<10 ppm, and N<10 ppm.Results are shown in Table 1 as well.

In this case, the effects of sublimation purification were sufficient,and the intended purity of 4N5 (99.995%) or more in the presentapplication was able to be achieved. This is a preferred Example.

Example 1-2

Sublimation/distillation purification was performed at a heatingtemperature of 1200° C. and a sublimation rate of 103 (g/h).

Impurities in the metal Mn after this sublimation purification were B:0.46 ppm, Mg: 0.17 ppm, Al: 1.4 ppm, Si: 1.2 ppm, S: 0.02 ppm, Ca: 2.1ppm, Cr: 0.69 ppm, Fe: 0.21 ppm, Ni: 0.08 ppm, O<10 ppm, and N<10 ppm.Results are also shown in Table 1 as well.

In this case, the effects of sublimation purification were sufficient,and the intended purity of 5N (99.999%) or more in the presentapplication was able to be achieved. This is a further preferredExample.

Example 1-3

Sublimation/distillation purification was performed at a heatingtemperature of 1250° C. and a sublimation rate of 184 (g/h).

Impurities in the metal Mn after this sublimation purification were B:1.1 ppm, Mg<0.01 ppm, Al: 0.85 ppm, Si: 3.6 ppm, S: 0.04 ppm, Ca: 1.9ppm, Cr: 1.4 ppm, Fe: 0.77 ppm, Ni: 0.18 ppm, O<10 ppm, and N<10 ppm.Results are shown in Table 1 as well.

In this case, the effects of sublimation purification were sufficient,and the intended purity of 5N (99.999%) or more in the presentapplication was able to be achieved. This is a preferred Example.

INDUSTRIAL APPLICABILITY

According to the present invention, Mn having ultra-high purity can beobtained by a relatively simple manufacturing process at a reducedmanufacturing cost. Therefore, it is useful as: a metal Mn used forwiring materials, electronic component materials such as magneticmaterials (magnetic recording heads), and semiconductor componentmaterials; and a sputtering target material for forming a thin filmthereof, in particular an Mn-containing thin film. Since the presentinvention can be manufactured with a common furnace without the need forspecial equipment, and a high purity Mn can be obtained at a lower costand higher yield as compared with the conventional distillation method,it can be said that it has high value regarding industrial use.

1. A method for manufacturing a high purity Mn, the method comprising:placing an Mn raw material in a magnesia crucible to perform meltingwith the use of a vacuum induction melting furnace (VIM furnace) at amelting temperature of 1240 to 1400° C. under an inert atmosphere of 500Torr or less; then adding calcium (Ca) in a range between 0.5 and 2.0%of the weight of Mn to perform deoxidation and desulfurization; castingthe resultant in an iron mold after the completion of the deoxidationand desulfurization to manufacture an ingot; then placing the Mn ingotin a magnesia crucible to perform melting with the use of a vacuuminduction melting furnace (VIM furnace) at a melting temperature, whichis adjusted to 1200 to 1450° C. and maintained for 10 to 60 minutes,under an inert atmosphere of 200 Torr or less; casting the resultant inan iron mold to manufacture an ingot, then placing the metal Mn ingot inan alumina crucible; reducing pressure to 0.01 to 1 Torr with a vacuumpump; and then heating to develop a sublimation and distillationreaction for obtaining a high purity Mn.
 2. The method for manufacturinga high purity Mn according to claim 1, comprising, when performing thesublimation and distillation, placing the metal Mn ingot in acylindrical alumina crucible and vertically aligning a similarly-shapedalumina cylinder on top of the cylindrical crucible to develop asublimation and distillation reaction so that Mn deposits inside theupper alumina cylinder.
 3. The method for manufacturing a high purity Mnaccording to claim 2, comprising attaching a carbon heater to theoutside of a cylindrical alumina crucible into which the metal Mn ingotis placed, and performing heating.
 4. The method for manufacturing ahigh purity Mn according to claim 3, comprising performing sublimationand distillation purification at 1100 to 1250° C. and a sublimation anddistillation rate of 20 to 184 g/h.
 5. The method for manufacturing ahigh purity Mn according to claim 4, comprising, when the depositedamount of sublimated/distilled Mn reaches 70% of the weight of the metalMn ingot charged into the alumina crucible during the sublimation anddistillation step, stopping the sublimation/distillation step. 6.-9.(canceled)
 10. The method for manufacturing a high purity Mn accordingto claim 1, comprising attaching a carbon heater to the outside of acylindrical alumina crucible into which the metal Mn ingot is placed,and performing heating.
 11. The method for manufacturing a high purityMn according to claim 1, comprising performing sublimation anddistillation purification at 1100 to 1250° C. and a sublimation anddistillation rate of 20 to 184 g/h.
 12. The method for manufacturing ahigh purity Mn according to claim 1, comprising, when the depositedamount of sublimated/distilled Mn reaches 70% of the weight of the metalMn ingot charged into the alumina crucible during the sublimation anddistillation step, stopping the sublimation/distillation step.